The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Typically, when an engine is operating, both air and fuel are supplied to a combustion chamber of a cylinder. Fuel is injected by an injector, while air is supplied to the combustion chamber through the operation of a cam and a valve provided in the cylinder head. At this time, it is required to adjust a point in time to open the valve, or the amount of the opening of the valve, depending on the operation area of the engine. In the related art, in order to blow air taken in by the cam and the valve into the combustion chamber, the valve disposed on the upper surface of the combustion chamber is opened and closed by the cam using a hydraulic circuit.
FIG. 1 illustrates a valve opening and closing apparatus of the related art. The valve opening and closing apparatus of the related art controls a point in time to open a valve 10 using a cam 20 and the amount of the opening of the valve 10 using a hydraulic circuit. However, the hydraulic circuit is composed of a plurality of parts, such as a pump unit 30, a high-pressure chamber 40, an accumulator 50, a deaerator 60, a pressure chamber 70, a check valve 80, a solenoid valve 90, and a brake unit 95, increasing the complexity, weight, and cost of the valve opening and closing apparatus of the related art. In addition, when a pressure-forming closed circuit has a large volume, the response of a hydraulic system becomes slow, degrading performance, which is problematic.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the foregoing is already known to those skilled in the art.